The present invention relates to removable cartridges for carrying optical disks in which the cartridge can be readily inserted into an optical disk drive and be usable for all purposes as if the optical disk were fixed within the optical disk drive.
More particularly, the present invention is directed to a light-tight optical disk cartridge designed to be used with optical media, such as electron trapping optical materials (ETOM), which are light sensitive.
Optical storage devices for use in storing computer and other data are well known in the art. Such devices are desirable because of their ability to store vastly more information per disk than known magnetic storage devices. While most of the known optical disk drive devices perform read-only functions, there are presently known write-once-read-many times (WORM) and erasable optical memory systems. All of the known (with the exception of the instant assignee) erasable optical storage device technologies involve techniques that require heat, which usually changes the physical or chemical structure of the materials in performing the write or erase function. In addition, performance of the media utilized with such approaches can easily be degraded over time due to the high sensitivity of the media to impurities, impurity diffusion, oxidation and other imperfections that propagate into defects which may only show up after multiple switching cycles or after the manufacturing and testing of the devices.
In order to overcome the problems of prior art erasable optical disk drives, the assignee of the present invention has developed a new approach to optical disk storage in which the optical storage materials which provide the storage function of the erasable optical disk drive utilize electron trapping optical materials The electron trapping phenomenon is embodied by a class of materials which comprise an alkaline earth crystal typically doped with rare earth elements Thin crystalline forms of such materials may be formed on various substrate structures, such as glass or aluminum, in order to provide the disk storage medium.
Since the trapping phenomenon is a purely electronic process, read, write and erase operations can be performed in very short periods of time. In addition, the physical trapping phenomenon appears to offer a practically limitless media life.
The materials which may be used as the media for the optical disk described herein are the subject of, for example, U.S. Pat. Nos. 4,864,536 and 4,830,975. Other examples of materials useful as storage media on the ETOM optical disk described herein are disclosed in U.S. Pat. Nos. 4,839,092, 4,806,772 and 4,842,960. The disclosure of each of those patents is incorporated by reference herein.
Reference is made to each of the foregoing issued United States patents for an expanded discussion of the electron trapping and electron trapping optical memory media phenomena.
Known removable magnetic and optical disks have typically used several types of cartridge designs ranging from folded plastic sleeves for magnetic floppy disks to injection molded plastic casings with slide shutters for optical disks All of these designs are suited specifically for their individual application. They all have some features in common. All of these known designs provide a means of handling the disks without damaging the enclosed disk. They all also provide a method of maintaining environmental contaminants at a minimum while at the same time providing access to the center clamping hub for rotating the disk. Obviously, all of such magnetic and optical disk cartridge designs are removable from the disk drive with which they are used.
All of the known hard-cased disk cartridges are typically assembled using plastic pins molded into the corners of the casing. That method of assembly functions well for magnetic and optical media having a moderate or low sensitivity to light. Such disk cartridges are of a sturdy and functional design, which prevents fingerprints, dust and rough handling from damaging the information stored on the disk. However, such prior art cartridge designs do not provide, nor do they even consider providing, any method for preventing ambient light from reaching the enclosed disk.
U.S. Pat. No. 4,535,434, to Kashi, relates to a rotating optical disk in an environmentally sealed cartridge in which access to the disk is accomplished through a transparent section in the cartridge casing.
U.S. Pat. No. 4,542,495, to Ziegler et al., one of the co-inventors herein, relates to a sealed cartridge for an optical disk in which a window is utilized rather than a shutter through which the beams from the optical read/write head pass without opening the cartridge and exposing the disk to dust and other contaminants
U.S. Pat. No. 4,853,925, to Kaneuchi, relates to a cartridge for an information memory medium which includes a locking shutter fitted into parallel guide grooves in the slide direction. This patent also discloses sliding write protect tabs and a return spring activated locking mechanism.
U.S. Pat. No. 5,048,008, to Haruna, relates to a disk cartridge for either magnetic or optical media in which a split shutter is utilized. The two halves of the shutter slide apart to reveal the active surface of the disk. Dual coiled springs are utilized to operate the shutters.
U.S. Pat. No. 4,367,503, to Treseder, relates to a hermetically sealed magnetic disk container for holding a plurality of platters mounted on a spindle. The seal is designed to protect the disks from contamination by particulates.
U.S. Pat. No. 4,991,717, to May, relates to a light and moisture resistant packet for photographic sheet film which utilizes a hermetic adhesive seal having a reusable membrane.
U.S. Pat. No. 4,945,530, to Sandell, relates to a cartridge for optical data disks which has dual sliding doors mounted to a slider for movement in a groove formed by the cartridge halves. A locking lever is provided which prevents the disk from rotating when not in use.
U.S. Pat. No. 4,782,418, to Tanaka, relates to a disk cartridge having an elongated cover plate which is adapted to thoroughly and sealedly cover a slot of the disk cartridge.
U.S. Pat. No. 4,571,718, to Cahill et al., relates to a sealed magneto-optical disk cartridge with a magnetic hub. The disk is actuated through a transparent section of the cartridge.